OEMTOOLS 25039 Piston Ring Compressor (3-1/2"-7") Capacity: Fits 3-1/2 In. to 7 in Pistons Height: 3-1/2 In Designed With Double Friction Brake Adjustment and Hardened Tool Ratchet Constructed of High Grade Spring Steel with 1/4 In. Square Drive Adjuster Beaded Edge Prevents Tool from Entering Cylinder with Pistons